<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        a{
            background:url("images/bgc.png") no-repeat;
            width:120px;
            height: 50px;
            display:inline-block;
            text-align:center;
        }

        a:hover{
            background:url("images/bg.png");
        }
    </style>
</head>
<body>
   <a href="#">百度</a>
</body>
</html>